2000 Mustang A/C Issues...Help!!!

In post #18 you mentioned that the red wire #12 to the CCRM is "fed" from fuse 2.2, so I assumed just that. If there was no power to the wire, go back and check the source. I'll start over tomorrow with the CCRM plugged in.

Dude...this is really a F'ed up test thread. Please re-read the instructions. No where does it state to remove the CCRM.

Fuse F2.2 gets it's power from the CCRM. So that would explain why F2.2 has suddenly lost power on a car that otherwise works. Hence the reason for the note about unplugging the switch affecting the downstream results.

The tests are to be done with the CCRM installed. It would have never occured to me to mention that as a requirement of the test.

At this point, we should consider all of your tests invalid because I'm completely unsure HOW the tests were performed.

A VOM is a tool. As a tool, it's usefulness depends to a great deal on the experience of the operator. Electrical issues can be a real PIA. The typical troubleshooting methods involve performing tests. Based upon the results, additional tests are performed. A bogus test result can set up a "wild goose chase" of epic proporations. You sir may have just been saved a great deal of wasted effort.

Click to expand...

I don't think this thread is F'ed up at all. I'm sure someone will read through all this info and find out what they should and shouldn't do to solve this same problem on their car. After all isn't that the whole purpose of a forum like this. It's just another tool to use, like a VOM( which I do know how to use)to help fix a problem yourself so you don't have to pay some shop or even worse, the local dealership.

As a follow-up, I have repeated all tests with nothing disconnected and have verified the following:

All relevant fuses pulled and checked, OK
+12 volts with AC and key on to high pressure switch DG/OG
4 ohms CCRM pin#15 to battery negative
+12 volts at CCRM pin #21
+12 volts at CCRM pin #12 with key on
OBDII scanner shows no trouble codes
With key on and CCRM pin #22 grounded, the clutch WILL NOT engage
Clutch WILL engage when supplied with 12 volts directly from the battery

If I haven't missed anything, then I will assume the CCRM is bad. Apparently there is a difference between the 3.8L and the 3.9L module. Dealership wants $240, all of the local parts houses that I called, including NAPA, said that the 3.9L unit is not available. Salvage yards here have 00-04 3.8's but no 3.9's. Called Rockauto, they don't offer a replacement either. Looked on ebay and found a used one for $65, but this would be my last resort.

Is there any other model or year that uses the same module as mine, part #XR3F-12B581-AC? Or do you know of another on-line source to keep me from having to go to the dealer? Thanks in advance for your reply.

SN Certified Technician

4 Ohms back to the battery is high. Don't know if it's high enough to cause issues. If you wanted to be through, you could run a temporary ground back to battery negative and see if any difference.

If this were my car, I would replace the CCRM. Good work!

Consider getting a re-man unit from your local autoparts store.

Ford uses the same CCRM in multiple applications. Try this. Go to Home Page | O'Reilly Auto Parts enter the model information and search for CCRM. There is a compatibility tab that will let you know what other cars use the same part.

OK, this thing is fixed and blowing cold air again. I was searching for my exact part number for a replacement and found the following thread on the Mustang 3.7 forum. I followed the instructions and was also able to get the relay from Radio Shack and repair the module for $5. FWIW, I called the ford dealer again this morning to double check part numbers. According to the parts guy, all 3.8L and 3.9L V-6 Mustangs from September 2000 through 2004 use the same CCRM.

How to fix A/C CCRM

I had to post this somewhere, since I found out that the CCRM module that is failing to turn on the a/c clutch can be easily and cheaply repaired.

I have a 2000 Ford Mustang whose a/s stopped working a last week. After some probing around with a meter I came to isolate the problem to a malfunctioning CCRM. The PCM was applying 12vdc to pin 22 of the CCRM, but NO 12vdc to the a/c compressor clutch was appearing on pin 23. This suggested a faulty WAC Relay inside the CCRM case.

I called my local Ford dealer, $211 for a new CCRM!!! Ouch!! Let me first see what is wrong with the CCRM!!

I removed the the CCRM from the car, drilled out the fasteners holding the case and relay circuit board together, and repeated the test using a small battery charger as a power source. I applied 12vdc across pins 22 (+) and 15 (-) of the CCRM (the coil of the WAC Relay). At the same time my wife was holding an ohm meter across the contacts of the WAC Relay (pins 21 & 23 of the CCRM). I could hear the relay click, but the ohm meter showed no activity across pins 21 & 23. The relay was in fact bad.

Hoping to find a relay that was "something close" that I could make work I decided to take the CCRM circuit board with relays to the local Radio Shack to see what they had. Well, not only did I find a relay that was small enough to fit in the same space as the original WAC relay, it also had the EXACT hole pattern (solder pins) on it! It was an exact fit!! I purchased the relay for $4.50 including tax. I very carefully "nipped" away the old relay with a pair of sharp wire cutters "dikes" until only the small solder posts soldered to the circuit board was all that was left of the old relay. These came out easily with a 700watt soldering iron. BE careful and take it easy and do not damge the board! Do not force the removal of any part. If you have to desolder if you're having trouble nipping the old relay away! I cleaned the board up, then soldered the new relay in. Tested it out with the small battery charger as before, this time it tested good. Rivited the circuit board and case back together with aluminum rivits. Plugged it into the car's wiring harness and BINGO!! the repair worked great!! The a/c is working again.

For those of you who may want to try this repair get Radio Shack partno 275-005 relay. The relay EXACTLY replaced the WAC relay in the CCRM circuit board - the smaller of the five CCRM relays. The connector on the CCRM is clearly marked with pin numbers. The WAC relay (turns on compressor clutch) coil is across pins 15 & 22. The contacts of this same relay are across pins 21 & 23.